Effect Of Nitriding Treatment On Microstructure And Properties Of Fe-ni Based Alloy Coated/Mn13 Steel

In this paper,aiming at the defects of high manganese steel under low stress condition,while maintaining good strength and toughness under high stress impact,the exploration of Fe-Ni based alloy coating on high manganese steel surface plasma cladding is carried out.After the surface plasma cladding of Fe-Ni based alloy coating on high manganese steel,Fe-Ni based alloy coating/high manganese steel material is studied.The evolution of microstructure and properties after solid solution treatment,solid solution and aging treatment,solid solution and ion nitriding,and the influence of the microstructure and properties of the Fe-Ni based alloy coating/high manganese steel are explored.It provides a reference for the subsequent preparation of high and low impact metal base wear resistant coating on the surface of high manganese steel.The test results show that the microstructure of Fe-Ni based alloy coating is plate martensite and a small amount of retained austenite after cladding,and the heat affected zone is Wechsler structure,and the matrix is composed of austenite and small amount of pearlite.The microstructure of Fe-Ni based alloy coating/high manganese steel after solid solution at 820℃for 1 hours is plate martensite and a very small amount of austenite.The microstructure of the heat affected zone is transformed into granular bainite and acicular ferrite.After solid solution,most of the matrix is austenite and a very small amount of pearlite,and the grain is refined.After solid solution of Fe-Ni based alloy coating/high manganese steel,the microstructure of the cladding layer is mainly plate martensitic structure after 4 hours of aging at 300℃⁴00℃.The main phase consists ofα-Fe,Co₃Fe₇ and iron nickel compounds,the precipitation strengthening phase is FeCo and a small amount of Ni₃Mo and Mo_0.25.25 Ni_0.75,and the precipitated Ni₃Mo of the cladding layer after aging at 500℃shows the Ni₃Mo display.It is increasing and having Ni₃Ti precipitation.After 600℃aging,the Ni₃Mo decreased,and the Ni₃Ti strengthening phase disappeared,and a small amount of Fe ₂Mo phase was formed.After the Fe-Ni based alloy coating/high manganese steel is treated at 500℃after solid solution at 820℃,the thickness of the nitriding layer is about 100μm,the nitriding layer is granular nitride particles,the phases of the nitriding layer consist mainly of Fe₂Ni₂N and Fe_x N_y,and the microstructure and process of the Fe-Ni alloy coating and matrix below the nitriding layer.The samples of solid solution and aging treatment are similar.Friction and wear tests show that the friction coefficient of high manganese steel matrix is about 0.9 and the wear volume is 20mg at room temperature.The friction coefficient of Fe-Ni based alloy coating at room temperature is 0.75,the wear amount is11.2mg,the friction coefficient is 0.68 after solid solution,the wear amount is 10.1mg,and the wear coefficient and wear amount are reduced.After solid s olution of Fe-Ni based alloy coating/high manganese steel,the friction coefficient and wear amount of the cladding layer decreased first and then increased after 4 hours of aging at 300℃⁶00℃.The minimum value of friction coefficient after aging at 50 0℃was 0.5,the wear amount was 6.1mg,and the wear resistance was greatly improved.The friction coefficient of Fe-Ni based alloy coating/high manganese steel was 0.4 and 5.3mg after4 hour ion nitriding at 500℃after solid solution at 820℃.The impact toughness of the matrix is 150.33J/cm²,and the fracture morphology of the impact specimen is composed of many large and deep dimples,and there are many ripping edges,which are typical ductile fracture.After the cladding,the impact toughness of the Fe-Ni based alloy coating/high manganese steel material is only71.52J/cm²,the impact toughness is 80.22 J/cm² after solid solution,and the impact toughness increases significantly with the temperature rising at 300 to 500℃,and the impact toughness is 130.04J/cm² at 500℃.As the temperature rises again,the Fe-Ni base alloy coating is added.The impact toughness of layer/high manganese steel decreases.After nitriding at 500℃aging time,the impact toughness of the specimen is 92 J/cm²,and the impact toughness decreases with the aging temperature of 500℃.To sum up,the Fe-Ni based alloy coating/high manganese steel is treated with ion nitriding after solid solution.The hardness and wear resistance of the Fe-Ni based alloy coating can be significantly improved,and the impact toughness is slightly reduced.